1. Field of the Invention
This invention relates to a method for setting in advance a travel time in a required section of road on a passage route and a system for implementing the method, and also a method and a system of performing route calculation for navigation or the like using the method of setting the travel time.
2. Description of the Related Art
Recent years, navigation systems for guiding a conveyance such as an automobile to a destination desired by a user are becoming widely available.
The navigation system calculates a route connecting a starting location and a destination location based on requirements established by a user, and guides the user along a route determined by the resulting route calculation. The user can establish various requirements, e.g., distance priority, kinds of roadways making up the route such as a national road, toll road and expressway/motorway, use or non-use of a ferry boat, and traffic restrictions, for allowing the desired route calculation to be done.
However, the route calculation in the navigation system as described above does not conventionally involve actual traffic situations such as a traffic jam. If the route calculation is done on the basis of the requirement, for example, of the shortest route or of use of an expressway/motorway, the automobile may not always arrive at the destination location in the minimum time. There may be a situation in which the automobile is caught in a traffic jam on the way and much more time is required for travelling to the destination location than that required for travelling along an alternative route that includes a detour.
It has been supposed that in order to arrive at the destination location in the minimum time, the time for travelling a required section of road on the route should be set in advance for making the route calculation involving the set travel time.
However, the traffic situation varies every moment and differs according to the time of day. If the route calculation is made involving a travel time assumed across the board, the route calculation is not always made in line with the actual condition.
Accordingly, it is impossible to solve the aforementioned problem.